Emerging Research on Isradipine
Isradipine is a medication currently used to treat high blood pressure and goes by the brand name of DynaCirc®. It is classified as a calcium channel blocker. Isradipine caught the attention of researchers for Parkinson’s disease (PD) when data from large clinical studies showed that people taking isradipine had a lower risk of developing PD.
It is thought that in dopamine neurons in the brain, neurons which die in Parkinson’s disease, the entry of calcium in these neurons over time leads to damage. Isradipine blocks the activity of specific channels in the neuron that allow the calcium to enter, thus preventing the death of the neurons (nerve cells) that produce dopamine and may slow the progression of PD.
Dopamine is the neurotransmitter (chemical messenger) that is responsible for producing smooth, purposeful movement. PD damages the dopamine-producing neurons which causes the motor symptoms of PD, such as stiffness, slowness of movement, and tremor.1
Isradipine is currently in a Phase III clinical trial called the Safety, Tolerability and Efficacy Assessment of DynaCirc for PD (STEADY-PD). There are four different stages of clinical trials that medications go through:
- Phase I: the researchers test a new drug on a small group of people to evaluate its safety, determine a safe dose, and evaluate any potential side effects
- Phase II: a larger group of people are given the drug to determine its effectiveness and further evaluate safety
- Phase III: the drug is given to large groups of people to confirm its effectiveness, evaluate side effects, compare it to existing treatments, and identify any additional information about how to use the drug safely
- Phase IV: additional studies done after the drug is marketed gather information on long-term use2
How soon will the trial be completed?
Patients in the STEADY-PD clinical trial will take isradipine for many months, and the last person is expected to be finished with the trial in November 2018. Final results will take several months after that to tabulate. Assuming results are positive, approval by the U.S. Food and Drug Administration (FDA) could be soon after, since isradipine is already an available drug.1
Current known side effects of isradipine
Because isradipine is currently used for the treatment of high blood pressure, many of the side effects with its use are known. Side effects experienced by people taking isradipine include headache, dizziness, flushing, fast heartbeat, excessive tiredness, upset stomach, vomiting, or diarrhea. Occasionally, people taking isradipine experience serious side effects requiring immediate medical attention, such as chest pain, difficulty breathing, difficulty swallowing, fainting, rash, or swelling of the face, eyes, lips, tongue, arms, or legs.3
Should people with PD start taking isradipine now?
While the research results to date are exciting, it is not yet known if isradipine has beneficial effects on PD. Data from the trial will provide more information on its effectiveness in people with PD. In addition, low blood pressure is a common symptom of PD, so this medication may worsen the condition.1
What is a calcium channel blocker?
Isradipine is a calcium channel blocker. It works by preventing calcium from entering the cells. In the heart and blood vessels, this results in lower blood pressure. Scientists believe that, in the brain, isradipine may work by targeting a specific calcium channel that plays a role in the cause of PD.1,4